The short answer: a mycotoxin is a toxic compound produced by certain molds. It is not the mold itself and not a spore. Mycotoxins are far smaller, they settle on surfaces and into soft contents, and they remain after the mold that made them is dead or removed. This is why a completed remediation can leave a building that still does not feel right.
Mold, spores and mycotoxins are three different things
Mold is the organism — the living colony, the visible growth.
Spores are how it reproduces. Think seeds. They are what most air testing counts, because they are large enough to capture and identify.
Mycotoxins are chemical byproducts that some molds produce as they grow. They are not alive, so they cannot be killed. They are removed, degraded, or they stay where they are.
That last distinction is the one that matters practically. A product that kills mold effectively can still leave every mycotoxin in the building exactly where it was.
The ones found in water-damaged buildings
Hundreds are known. A handful come up repeatedly in indoor environments:
- Trichothecenes — produced by Stachybotrys chartarum, the species usually meant by "black mold", among others.
- Gliotoxin — associated with Aspergillus fumigatus.
- Aflatoxins — from Aspergillus flavus and Aspergillus parasiticus. The most studied group, largely because of food-supply contamination.
- Ochratoxin A — from various Aspergillus and Penicillium species.
- Fumonisins — mainly Fusarium.
- Zearalenone — also Fusarium.
Which are present depends on which species grew, on what material, and under what conditions. The same species does not always produce the same compounds.
Why standard testing usually misses them
Common indoor air testing counts spores. Spore trap sampling and culture plates both work on particles large enough to trap and identify.
Mycotoxins are orders of magnitude smaller, they bind to dust and surfaces rather than staying airborne, and detecting them requires different methods — typically dust sampling with laboratory analysis rather than an air pump.
So a clearance test can legitimately pass on spore counts while mycotoxin residue remains on contents. That is not the test failing. It is the test measuring what it measures.
Why remediation does not remove them
Remediation is built around the organism: find the moisture, contain the area, remove the colonized material, HEPA vacuum, verify spore counts.
Every step in that sequence targets mold or spores. None of it is designed around a chemical residue that has already settled into the contents of the room. The material carrying the colony leaves the building. The residue that spread beyond it does not.
This is the gap. It is also the most common explanation for a house that was properly remediated and still feels wrong.
How mycotoxins are actually removed
Because they are chemical rather than biological, killing is not the relevant verb. The options are physical removal or breaking the molecule apart.
Physical removal — HEPA vacuuming and thorough surface cleaning gets a meaningful share of what is on hard surfaces. It does less for soft contents.
Molecular breakdown — enzymes cleave the bonds holding the compound together, so it stops being that compound. This is the approach MycotoxinKlear takes, and it is the reason it is a separate product from the mold stain removers.
Disposal — for porous items that stayed wet and grew mold internally, removal from the building is still the honest answer.
What does not work: bleaching, which lightens a stain and leaves the chemistry alone, and fragrance-based odor products, which change what a room smells like and nothing else.
A note on health
We make cleaning products, and we are not going to tell you what mycotoxins do in a human body. That is genuinely contested territory in the literature and it belongs with a qualified practitioner, not a company that sells you a gallon of cleaner.
What is not contested is the building science: certain molds produce these compounds, the compounds persist on surfaces and in contents after the mold is gone, and standard remediation is not designed to clear them. That part we can speak to.
Common questions
Is a mycotoxin the same as mold?
No. Mold is the organism. Mycotoxins are chemical compounds some molds produce. Removing the mold does not remove them.
Can mycotoxins be killed?
They are not alive, so no. They are removed physically or broken down at the molecular level.
Do mycotoxins stay after mold is removed?
Yes, and this is the central point. They remain on surfaces and in soft contents until something specifically addresses them.
Does a normal mold test detect mycotoxins?
Usually not. Standard air testing counts spores. Mycotoxin detection generally requires dust sampling with laboratory analysis.
Does bleach destroy mycotoxins?
No. Bleach lightens staining and leaves the underlying material, including mycotoxin residue, behind.
